To maximise crop yields it has become essential to eliminate competing growths to allow the specific crops to grow unhindered. To this end the chemical industry has developed a range of herbicides to combat almost every weed. Similarly to facilitate mechanical harvesting it has been found necessary to either desiccate the foliage of potatoes and alfalfa or defoliate the cotton leaves before the cotton is plucked.
The man on the land knows however that no herbicide gives a complete strike rate so a burgeoning sub-industry has developed by which the efficacy of herbicides can be improved. Many names have been used to describe such compounds including "suffactants", "spreaders", "crop oil concentrates" and "spray adjuvants".
To overcome the problem in general for the industry and in particular for its own herbicides the BASF organisation patented systems in 1989 (U.S. Pat. No. 4,834,908 "Antagonism Defeating Crop Oil Concentrates" and Australian Patent 625194 "Adjuvants for use with Crop Protection Agents"). These systems are based on a concentrate comprising in essence 20-90% of a fatty acid ester, 4-40% of an anionic surfactant selected from the partial sulphate and phosphate esters of ethoxylates and from 7-20% of a fatty acid. A 100 parts of this blend is added to 140 parts of a hydrocarbon.
In the field, the system has been by-passed by the use of the simple methyl fatty esters emulsified with suffactants.
Another approach has been disclosed in an article entitled "Small Grass and Grass Weed Response to BAS-514 with Adjuvants" (Manthey et al) in Volume 4 Issue 2 of Weed Technology. The use of methyl, ethyl and butyl estefified sunflower oil is discussed as adjuvants for BAS-514. This study showed enhancing of BAS-514 by their use. There was no noted significant difference in efficacy between methyl, ethyl and butyl esters.
It is recognised that even these products are not optimising the efficacy of the herbicides.
To facilitate the gathering of potatoes and alfalfa seed, current practice is to desiccate the growing plants' foliage before harvest. Certain cationic materials are recommended with products such as DES-I-CATE and DIQUAT HERBICIDE - HA being well known on the field. It has also been found that their effectiveness may be enhanced by use of adjuvants such as AD-IT which is based on emulsified methyl oleate.
Similar to the current adjuvants for herbicides neither the total effectiveness, nor the rate of the desiccation is completely satisfactory for the farmer.
While the mechanical harvesting of crops such as cotton, tomatoes and beans has lowered production costs, it has also created new problems. In the case of cotton, mechanical harvesting has created perplexing problems at gins and textile mills. Such mechanically harvested cotton absorbs moisture from the spindles of the harvester and contains considerably more than the normal 5 to 15 percent of trash present in hand-picked cotton. Particularly bothersome is leaf material which is one of the most difficult types of trash to remove. This additional moisture and trash in mechanically harvested cotton frequently complicates ginning operations and raises the costs of textile manufacturing by requiring additional steps in cleaning the cotton at the mill.
Recent efforts have been directed toward the development of various chemical treatments for the crop plant in an effort to overcome the objectionable attributes of mechanically harvested cotton. For example, processes have been suggested in recent years which have as their objective to provide increased yields of the desired crop and/or to inhibit rank growth. Such processes have been effective in some respects. However, some of the prior art methods require the use of expensive surfactants in order to obtain satisfactory application of the chemical product to the plant. Other prior art methods produce an insufficient increase in the crop yield and/or decreases in rank growth for economic utilisation.
As the answer to this need, a plant growth regulator and its method of use were patented in 1984 "Plant Growth Regulator and Method for the Use Thereof" (U.S. Pat. No. 4,439,224). Whilst significant improvement was achieved, decreased trash limits continue to be set by the mills demanding further improvements in the level of defoliation.